Fluid-biased hydraulic control valve

ABSTRACT

A hydraulic control valve is provided having a solenoid body, an energizable coil, and an armature positioned adjacent the coil. A valve stem extends from the armature. The coil is energizable to move the armature and the valve stem from a first position to a second position. The valve body, the armature and the valve stem are configured so that the armature and the valve stem are biased to the first position by pressurized fluid, allowing the armature to operate without a biasing spring.

TECHNICAL FIELD

The present invention relates to an electrically operated hydrauliccontrol mechanism such as a solenoid valve.

BACKGROUND OF THE INVENTION

Solenoid control valves for hydraulic control systems are used tocontrol oil under pressure that may be used to switch latch pins inswitching lifters and lash adjusters in engine valve systems. Valvelifters are engine components that control the opening and closing ofexhaust and intake valves in an engine. Lash adjusters may also be usedto deactivate exhaust and intake valves in an engine. Engine valves maybe selectively deactivated or locked out to disable operation of somecylinders in an engine when power demands on an engine are reduced. Bydeactivating cylinders, fuel efficiency of an engine may be improved.

Engine deactivating solenoid control valves must operate with minimumresponse times to maximize engine efficiency. Valve response timesinclude valve activation response times and deactivation response times.Solenoid control valves apply a magnetic force to an armature that movesa control valve stem by activating a coil to move the armature against abiasing force that is typically provided by a spring. The magnetic forceapplied by the solenoid to the armature and in turn to the control valvestem should be maximized to reduce response time. The magnetic forceapplied by the coil can be increased by increasing the size of the coil.However, cost and weight reduction considerations tend to limit the sizeof the coil. Deactivation response times are adversely impacted by valveclosure biasing springs, the force of which must be overcome before thevalve is opened. While this delay in response times in most applicationsis minimal, in variable valve actuation systems, the limited time windowfor valve activation and deactivation is critical and must be minimized.

SUMMARY OF THE INVENTION

A hydraulic control valve is provided having a solenoid body, anenergizable coil, and an armature positioned adjacent the coil. A valvestem extends from the armature. The coil is energizable to move thearmature and the valve stem from a first position to a second position.The first position may be a deenergized, closed position, and the secondposition may be an energized, open position. The valve body, thearmature and the valve stem are configured so that the armature and thevalve stem are biased to the first position by pressurized fluid,allowing the armature to operate without a biasing spring. Thus, thearmature is configured so that the net fluid forces contribute toclosing the valve, providing a relatively quick valve actuation responsetime. If no biasing spring is used, cost and assembly time, as well asresponse time, are minimized. Additionally, the solenoid may be weaker,and therefore less expensive, as no spring biasing force needs to beovercome.

In one embodiment, the armature and the valve stem include a firstpoppet and a second poppet, and the valve body defines a supply chamberwith a first seat, a second seat, and a control chamber between thefirst and second seats. The first poppet is configured to sit at thefirst seat and the second poppet is configured to be spaced from thesecond seat in the first position to prevent pressurized fluid flow pastthe first seat and to exhaust fluid from the control chamber past thesecond seat. The first poppet is configured to be spaced from the firstseat and the second poppet is configured to sit at the second seat inthe second position to permit flow of pressurized fluid from the supplychamber to the control chamber and prevent flow from the control chamberto the exhaust chamber.

The hydraulic control valve may be mounted to an engine such that thearmature falls to the second position when the engine is off and thecoil is not energized, thereby moving the first poppet off of the seatto open the supply chamber to the control chamber. Thus, due to gravity,the armature is in the same position as the energized, engine—onposition when the engine is off and the coil is not energized. When theengine is subsequently restarted, with the coil still deenergized, aircan thereby expel from the supply chamber to the control chamber, andfurther to the exhaust when the armature and valve stem move to thefirst position due to pressurized oil acting on the second poppet.Expelling any air in the system enables a quicker, more controlledresponse of the valve.

A hydraulic control circuit is provided with an electromagnetic actuatorselectively actuatable to create a flux path, a valve body having a seatpast which a fluid under pressure is selectively permitted to flow, andan armature that is selectively moved in a first direction byelectromagnetic flux. The armature defines a poppet that is moved in thefirst direction relative to the seat from a closed position in whichfluid flow past the seat is prevented to an open position in which fluidflow past the seat is permitted, the armature being biased to the closedposition by operation of the fluid under pressure.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a solenoid valve;

FIG. 2 is an exploded perspective view of the solenoid valve shown inFIG. 1;

FIG. 3 is a cross-sectional view taken along the plane of section line3-3 in FIG. 1 showing the valve in a first, closed and deenergizedposition; and

FIG. 4 is a partial cross-sectional view similar to FIG. 3 of the valvein a second, open and energized position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a solenoid valve 10, for example, such as that usedto deactivate lifters or operate a dual lift system in an internalcombustion engine or diesel engine is illustrated. The solenoid valve 10may also be referred to as an electromagnetic actuator. The solenoidvalve 10 is installed in an engine 12. The solenoid valve 10 includes asolenoid portion 16 and a valve body 18.

Referring to FIGS. 2 and 3, the solenoid valve 10 is shown to include asolenoid can 20 that houses a coil 22 that powers the solenoid valve 10.A pole piece 24 is assembled within the solenoid can 20. The pole piece24 defines part of the flux path for the coil 22. A flux collectorinsert 26 is disposed within the solenoid can 20 and also forms part ofthe flux path for the coil 22.

An armature 28 is acted upon by the flux created by energizing the coil22 to shift the solenoid valve 10 from a normally closed position asshown in FIG. 3 to the open position as shown in FIG. 4. An air gap 30is provided between a radially-extending face 31 of the pole piece 24and a radially-extending face 33 of the armature 28. The air gap 30 maybe adjusted by adjusting the pole piece 24 relative to the armature 28.A relief groove 34, shown in FIG. 2, is provided in the armature 28 thatfacilitates flow of oil under pressure axially across the armature 28.The relief groove 34 is also referred to as a conduit. Alternatively, aconduit may be formed in the valve body 18 adjacent the armature 28 toprovide flow of pressurized oil across the armature 28. The fluxcollector insert 26 may be inserted adjacent to the coil 22 and thevalve body 18 in a molded one-piece or multiple-piece body 40.

The valve body 18 defines an oil intake chamber 41, also referred to asa supply chamber, in which the armature 28 is disposed and thatinitially receives oil under pressure. The valve body also defines anintermediate chamber 42, also referred to as a control chamber. Aplurality of O-ring grooves 43 are provided on the exterior of the valvebody 18 that each receives one of a plurality of seals 44. The seals 44establish a seal between the valve portion 18 and the engine 12. Themolded body 40 defines an internal coil receptacle 46, or bobbin, thatextends into the solenoid portion 16. The coil 22 is shown only in part,but it is understood that the coil 22 fills the coil receptacle 46. Thebody 40 may be formed as a one-piece integral plastic molded part, asillustrated, or could be formed in pieces and assembled together. Thecoil 22 is wrapped around the coil receptacle 46.

A valve stem 48 has a portion 50 that is received within an opening 52in the armature 28. The position of the control valve stem 48 may beadjusted relative to the armature 28 by a threaded connection or by apress-fit between the stem 48 and the armature 28. The armature 28includes a poppet 54 that is moved relative to the valve seat 56 inresponse to pressure changes, as will be more fully described below. Anexhaust poppet 60 is provided on one end of the control valve stem 48 tomove relative to a valve seat 62 to open and close an exhaust port 70.

A supply gallery 64 is provided in the engine 12 to provide pressure P₁to the oil intake chamber 41 that is defined in the valve body 18. Acontrol gallery 68 is provided in the engine 12 that is normallymaintained at control pressure P₂. An exhaust gallery 71, also providedin the engine, is in communication with the exhaust port 70 and isported to ambient pressure and may be referred to as “P₀”. Theintermediate chamber 42 goes to Pressure P₀ when the exhaust port 70 isopened.

Referring to FIG. 4, the solenoid valve 10 is shown in the openposition. The coil 22 is energized to retract the armature 28 toward thecoil 22. The poppet 54 opens the valve seat 56 to provide pressure P₁from the oil intake chamber 41 to the intermediate chamber 42, and theexhaust poppet 60 sits at seat 62 to close the exhaust port 70.

Referring to FIGS. 2-4, the valve body 18 includes a supply opening 63that receives oil under pressure from a supply gallery 64 that is incommunication with the oil intake chamber 41 and the valve seat 56. Whenthe valve seat 56 is open, the intake chamber 41 is in communicationwith the intermediate chamber 42. Oil under pressure is provided throughan outlet opening 66, also referred to as a control port, and to acontrol gallery 68. An exhaust port 70 is provided at the inboard end ofthe valve body 40. Exhaust port 70 is in communication with exhaustgallery 71.

In operation, the valve 10 is normally closed as shown in FIG. 3 and isshifted to its open position as shown in FIG. 4 by energizing the coil22. The coil 22, when energized, reduces the air gap 30 formed betweenthe pole piece 24 and the armature 28. The armature 28 is shifted towardthe pole piece 24 by electromagnetic flux created by the coil 22. Oil inchamber 41 is in communication with the gap 30 through the relief groove34.

When in the normally closed position shown in FIG. 3, the poppet 54closes the valve seat 56, isolating the oil intake chamber 41, which isat P₁, from the intermediate chamber 42, which is at P₂. The oil underpressure in the oil intake chamber 41 biases the poppet 54 against thevalve seat 56. The area of the armature 28 affected by P₁ biases thearmature to the closed position as P₁ acts on the larger surface area offace 33 of the armature 28 at the gap 30 to provide biasing force in onedirection (i.e., in a direction to seat the poppet 54 at the seat 56,while pressurized fluid at P₁ acts on a smaller surface area 73 of thearmature in the chamber 41 in an opposing direction. The biasing forceapplied to the poppet 54 is intended to eliminate the need for a spring.Alternatively, a spring (not shown) may be incorporated to increase thebiasing force applied to the poppet 54.

When the coil 22 is energized, flux through the pole piece 24 and fluxcollector insert 26 pulls the armature 28 toward the pole piece 24, asshown in FIG. 4. The face-to-face orientation of the armature 28relative to the pole piece 24 subjects the armature 28 to exponentiallygreater magnetic force. Shifting the armature 28 causes the poppet 54 toopen relative to the valve seat 56, thereby providing pressure P₁ fromthe oil intake chamber 41 to the intermediate chamber 42. Theintermediate chamber 42 is normally maintained at pressure P₂ but isincreased to P₁ when the poppet 54 opens the valve seat 56 and thepoppet 60 closes valve seat 62 to close off the exhaust port 70. Thus,P₂ acts on the surface area of face 33 of the armature 28 and thesurface area 72 of the poppet 54 in one direction and on annular surfacearea 73 and surface area 74 of poppet 54 in an opposing direction.Because the affected surface area 33 is equal to the combined surfaceareas 73 and 74, the net force is that on surface area 72. This changein pressure increases the hydraulic pressure supplied to the enginevalve system to P₁. When the pressure provided to the engine valvesystem changes to P₁, selected engine valves may be deactivated by latchpins, lash adjusters or another controlled device (not shown) to therebydeactivate selected cylinders of the engine.

When the coil 22 is subsequently deenergized, with the forces due to theflux removed (i.e., the net force pulling the armature 28 toward thepole piece 24), the net fluid pressure on surface area 33 drives thearmature 28 to the normally closed, deenergized position of FIG. 3.Thus, the armature 28 is configured so that the net fluid forces (i.e.,net downward force acting on face 72) contributes to closing the valve10, with the chamber 42 exhausting to exhaust port 70, thereby providingrelatively quick valve actuation response time from the energized to thedeenergized position.

The valve 10 is provided with an air purging and self-cleaning feature.Specifically, the armature 28 is formed with a bypass slot 53, alsoreferred to as a bypass channel, to permit a limited amount of oil tomove from chamber 41 to chamber 42 when the valve 10 is closed,bypassing the seat 54. Alternatively, the bypass slot may be provided inthe body 18 adjacent the seat 54. The slot 53 also allows particles ofdirt to be expelled from chamber 41 with the oil, and thus functions asa “self-cleaning” feature of the valve. Additionally, air is purged fromthe chamber 41 through slot 53, thus preventing an air cushion actingagainst valve 10 moving to the energized position of FIG. 4 when thecoil 22 is subsequently energized. This allows quick transitioning fromthe deenergized to the energized position.

When the engine 12 is off so that no fluid pressure is provided in thevalve 10 and the coil 22 is deenergized, assuming that the valve 10 isinstalled in the engine 12 with the armature 28 above the pole pieceplug 24 (i.e., upside down with respect to the view shown in FIGS. 3 and4), gravity will cause the armature 28 to fall to the energized positionof FIG. 4 (although the coil is not energized). Thus, when the engine 12is started, pressurized oil will come up the supply gallery 64 and forceany air ahead of it out of the supply chamber 41 to the control chamber42, past the open seat 56 as the oil proceeds into chamber 41 and gap30, biasing the armature 28 to the closed, deenergized position of FIG.3. The air is expelled from chamber 42 to exhaust port 70 as the poppet62 unseats.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A hydraulic control valve comprising: a solenoid body; a selectivelyenergizable coil; an armature positioned adjacent the coil and having avalve stem extending therefrom; the coil being energizable to move thearmature and the valve stem from a first position to a second position;wherein the valve body, the armature and the valve stem are configuredso that the armature and the valve stem are biased to the first positionby pressurized fluid.
 2. The hydraulic control valve of claim 1, whereinthe hydraulic control valve is characterized by the absence of a springbiasing the armature and valve stem to the first position.
 3. Thehydraulic control valve of claim 1, wherein the armature and the valvestem include a first poppet and a second poppet; wherein the valve bodydefines a supply chamber with a first seat, a second seat, and a controlchamber between the first and second seats; wherein the first poppet isconfigured to sit at the first seat and the second poppet is configuredto be spaced from the second seat in the first position to substantiallyprevent pressurized fluid flow past the first seat and to exhaust fluidfrom the control chamber past the second seat; wherein the first poppetis configured to be spaced from the first seat and the second poppet isconfigured to sit at the second seat in the second position to permitflow of pressurized fluid from the supply chamber to the control chamberand prevent flow from the control chamber to an exhaust port.
 4. Thehydraulic control valve of claim 3, in combination with an engine;wherein the hydraulic control valve is mounted to the engine such thatthe armature falls to the second position when the engine is off and thecoil is not energized, thereby moving the first poppet off of the seatto open the supply chamber to the control chamber, air thereby expellingfrom the supply chamber to the control chamber and further expelling tothe exhaust port when the armature and valve stem move to the firstposition when the engine is restarted.
 5. The hydraulic control valve ofclaim 4, wherein the armature is configured so that an additional areaof the second poppet is exposed to pressurized fluid when the armaturetransitions from the second position to the first position, therebybiasing the armature to the first position.
 6. The hydraulic controlvalve of claim 4, wherein one of the valve body and the first poppetform a bypass channel at the first seat, allowing air to bleed from thesupply chamber to the control chamber through the bypass channel whenthe valve is in the first position.
 7. The hydraulic control valve ofclaim 1, further comprising: a pole piece positioned to establish a gapbetween the pole piece and the armature; wherein the armature isconfigured to route pressurized fluid between the gap and a side of thearmature opposite the pole piece and the gap; wherein a first area ofthe armature exposed to pressurized fluid in the gap is greater than asecond area of the armature exposed to pressurized fluid at the side ofthe armature opposite the gap, the armature thereby being biased awayfrom the pole piece by the fluid.
 8. The hydraulic control valve ofclaim 7, wherein the area exposed to fluid force biasing the valve tothe first position increases as the valve transitions from the secondposition to the first position and the gap between the armature and thepole piece increases.
 9. A hydraulic control circuit comprising: anelectromagnetic actuator selectively actuatable to create a flux path,the actuator including a valve body having a seat past which fluid underpressure is selectively permitted to flow; and an armature that isselectively moved in a first direction by electromagnetic flux, thearmature defining a poppet that is moved in the first direction relativeto the seat from a closed position in which fluid flow past the seat issubstantially prevented to an open position in which fluid flow past theseat is permitted, the armature being biased to the closed position byoperation of the fluid under pressure.
 10. The hydraulic control circuitof claim 9, wherein the poppet is a first poppet; wherein the valve bodydefines a second seat; wherein the armature is connected to a valve stemthat defines a second poppet that is moved with the armature in thefirst direction relative to the second seat from a first position inwhich fluid flow past the second seat is permitted to a second positionin which fluid flow past the second seat is prevented; and wherein thesecond poppet is biased toward the first position when the armature isbiased toward the closed position by the fluid under pressure.
 11. Thehydraulic control circuit of claim 10, wherein the first poppet and thesecond poppet are held in a fixed spatial relationship by the valvestem.
 12. The hydraulic control circuit of claim 9, wherein theelectromagnetic actuator is a solenoid valve that includes a coil thatis energizable to create the flux.
 13. The hydraulic control circuit ofclaim 9, wherein the valve body defines a first chamber to whichpressurized fluid is provided through a supply port; wherein the valvebody further defines a second chamber from which fluid exhausts to anexhaust port; and wherein the second chamber is in fluid flowcommunication with the first chamber when fluid is permitted to flowpast the seat.
 14. The hydraulic control circuit of claim 13, whereinthe armature is connected to a valve stem that defines a second poppetthat is moved with the armature relative to the exhaust port between aclosed position and an open position in the first direction, wherein thefirst poppet is open when the second poppet closes the exhaust port andthe first poppet is closed when the second poppet opens the exhaustport.
 15. A hydraulic control valve comprising: an energizable coil andan armature; a valve body defining a valve seat, an exhaust seat, asupply port, a control port, and an exhaust port; wherein the armatureincludes a first poppet seated at the valve seat when the coil is notenergized and substantially preventing pressurized fluid flow from thesupply port past the valve seat to the control port; wherein thearmature is shifted within the valve body by a magnetic force generatedby the energized coil to move the first poppet away from the valve seatto allow fluid flow from the supply port to the control port; a valvestem assembled to the armature and having an exhaust poppet that isspaced from the exhaust seat when the coil is not energized to allowfluid flow from the control port to the exhaust port, and is seated atthe exhaust seat to prevent fluid flow from the control port to theexhaust port when the coil is energized.
 16. The hydraulic control valveof claim 15, wherein the armature is configured so that an additionalarea of the second poppet is exposed to pressurized fluid when thearmature transitions from a second position in which the coil isenergized to a first position in which the coil is not energized,thereby biasing the armature to the first position.
 17. The hydrauliccontrol valve of claim 15, wherein one of the valve body and the firstpoppet form a bypass channel at the first seat, allowing air to bleedfrom the supply port to the control port through the bypass channel whenthe valve is in a first position in which the coil is not energized. 18.The hydraulic control valve of claim 17, wherein an area of the exhaustpoppet exposed to fluid force biasing the valve to the first positionincreases as the valve transitions from a second position in which thecoil is energized to the first position and a gap between the armatureand the pole piece increases.